Multivariate techniques in the systematic analysis of the kingsnakes, genus Lampropeltis : with emphasis on infraspecific variation, a preliminary study

The genus Lampropeltis is represented by six extant species from the Western hemisphere. Although subjected to considerable systematic study, definition of infraspecific populations continues to be debated. The present study is a preliminary reexamination of the genus for infraspecific variation. Each species is described and the literature on systematics, biogeography and paleontology of each as well as taxonomic characters and methods appropriate to the taxonomic study of the genus are reviewed. Current information about Pleistocene conditions which may have affected the evolutionary history of kingsnakes is also discussed.

Theoretical aspects of phylogenetic studies are discussed in general, with specific references to the literature of Lampropeltis. The present study proposes that use of computers, multivariate analysis techniques, computer manipulation of data bases, and computer graphics, can improve the rigor of systematic analysis. The present study uses eidostic, metric, and meristic data from five species of kingsnakes, Lampropeltis calligaster, L. getulus, L. pyromelana, L. triangulum, and L. zonata. Additional environmental data were obtained from the Geoecology Data Base. Data was analysed by Cluster Analysis, Factor Analysis, Multiple Regression, and Discriminant Analysis. Discriminant Analysis proved to be the most useful. Computer generated color graphics enhanced the study and their value to multivariate analyses and to systematic studies is discussed.

Results of all the various techniques are reported, and suggestions for future applications to systematic studies are offered. Conclusions specific to the systematics of Lampropeltis are drawn primarily from the results of Discriminant Analyses. At the level of species, Discriminant Analyses confirm the distinctions among the five species analysed. Lampropeltis zonata had to be omitted from the analysis of infraspecific variation. Subspecies of L. calligaster and L. pyromelapa were confirmed as distinct by Discriminant Analyses. The results for L. getulus and L. triangulum are more ambiguous.

The Discriminant Analyses also suggest that the definition of subspecies complexes would be appropriate for groups of subspecies of Lampropeltis getulus and L. triangulum. The subspecies complexes of the present study are defined by Discriminant Analyses, but also discussed in terms of biogeographical and paleontological considerations, and the boundaries were set using geographical boundaries likely to have been significant during the Pleistocene. L. getulus is divided into two complexes, one east and one west of the Mississippi River, L. triangulum is divided into three complexes, one east and one west of the Mississippi River, and a third occupying Middle America and northern South America.